In a typical sequence of a BICOM fabricating process the window for a transistor base is usually structured by means of an anisotropic plasma etching step. The window defined by a patterned resist layer is thus structured with straight side walls that extend through a polycrystalline silicon layer (hereinafter “poly”) covered with an oxide layer. For epitaxial (“EPI”) growing of a silicon layer in the base window an advanced trisilane (Si3H8) epitaxial process is a preferred option due to the low cost and high yield of that process. With shrinking component dimensions and increasing thickness of the polycrystalline silicon layer, however, the trisilane epitaxial process is not applicable due to the forming of residual poly stringers after structuring that epitaxial layer by etching, as will be explained in more detail with reference to the appending drawings. These stringers affect operation of the resulting circuit component.